Greenhouse gas emissions from New Zealand sheep and beef farms

This project aimed to develop a dataset containing animal policies, production efficiencies, and greenhouse gas (GHG) emissions of a large number of sheep and beef farms, and to examine the relationships between farm management and farm physical constraints, and GHG emissions. We used the farm-scale model Farmax to estimate feed inventories, livestock policies and GHG emissions of 170 New Zealand sheep and beef farms. Emissions were calculated from Farmax outputs using Agricultural Inventory methodology. We used a quantitative approach to cluster farms based on physical constraints and management attributes. Mean annual biological GHG emissions from the modelled farms were 3,662 kg CO2 equivalents (CO2-e) per effective hectare, and ranged from 157 to 7,096 kg CO2-e/effective ha. As stocking rate and animal product (wool + net carcass weight) per effective hectare increased, GHG emissions increased. However, there was considerable variability in the data; farms with GHG emissions of approximately 4,000 kg CO2-e/effective ha had an almost three-fold difference in animal product (range 129 to 360 kg/effective ha). Our work provides a holistic assessment of the farm-scale drivers of GHG emissions and a comprehensive current state of affairs or baseline from which future trends in farm-scale GHG emissions can be established.